By examination of developing and regenerating retinae with cytochemical, high resolution light microscope autoradiographic, and electron microscopic analyses, the following investigation will be undertaken: 1. Identification and quantification of correlative cytochemical and ultrastructural features and relationships of the cells of the retina, retinal pigment epithelium, and pars ciliaris during the histogenetic development of the retina in urodele amphibian, avian, and mammalian eyes. Through this approach it is intended to more properly define the developmental interactions influencing cellular migration and differentiation in the maturing retina. 2. Determination of the cellular contribution to retinal regeneration in all three species and of alterations in cytochemical features during the process of retinal regeneration through cytochemical microspectrophotometric and autoradiographic analysis of in vivo and in vitro cell studies at selected regeneration stages. 3. Evaluation of cellular characteristics between species at selected developmental and regeneration stages in an effort to elucidate the differentiative mechanism operant in the restriction of retinal regeneration in most adult vertebrates.